Tool torque limiter

ABSTRACT

A torque limiter can include a housing and a shaft. The housing can include a housing magnet enclosed within the housing. The shaft can be at least partially surrounded by the housing and can be rotatable within the housing. The shaft can include a shaft magnet integrated with the shaft to magnetically couple with the housing magnet to transmit a torque between the housing and the shaft and configured to uncouple from the housing magnet allowing the shaft to rotate within the housing when a threshold torque is reached.

CLAIM OF PRIORITY

This application is a continuation of U.S. application Ser. No.15/809,661, filed on Nov. 10, 2017, which claims the benefit of priorityto U.S. Provisional Application Ser. No. 62/420,899, filed on Nov. 11,2016, each of which is incorporated herein by reference in its entirety.

BACKGROUND

Torque limiters can be used to limit an amount of torque transferredbetween two objects, such as two shafts. Torque limiters are often usedwith tools, such as hand tools and power tools, to limit an amount oftorque transferred to a workpiece, such as a screw or bolt. Some torquelimiters rely on mechanical means to limit a transferred torque, makingthem susceptible to wear. Torque limiters can be found in surgical toolsand systems to limit the amount of torque applied to a work pieceinstalled in or utilized on a patient.

OVERVIEW

In one example, a torque limiter for limiting a torque transferred froma tool can include a housing and a shaft. The housing can be couplableat a proximal end to a tool, and the housing can include a housingmagnet enclosed within the housing. The shaft can be couplable at adistal end to a workpiece and can be enclosed by the housing. The shaftcan include a shaft magnet enclosed within the shaft and can beconfigured to magnetically couple with the housing magnet to transmit atorque between the housing and the shaft and can be configured touncouple from the housing magnet causing the shaft to rotate within thehousing when a threshold torque is reached.

The following, non-limiting examples, detail certain aspects of thepresent subject matter to solve the challenges and provide the benefitsdiscussed herein, among others.

Example 1 is a torque limiter for limiting a torque transferred from atool: a housing couplable at a proximal end to a tool, the housingcomprising: a housing magnet enclosed within the housing; and a shaftcouplable at a distal end to a workpiece and enclosed by the housing,the shaft comprising: a shaft magnet enclosed within the shaft andconfigured to magnetically couple with the housing magnet to transmit atorque between the housing and the shaft and configured to uncouple fromthe housing magnet causing the shaft to rotate within the housing when athreshold torque is reached.

In Example 2, the subject matter of Example 1 optionally includeswherein the housing further comprises: a plurality of housing magnetsdisposed around a central bore of the housing.

In Example 3, the subject matter of Example 2 optionally includeswherein the shaft further comprises: a plurality of shaft magnetsdisposed within the shaft to align with the plurality of housingmagnets.

In Example 4, the subject matter of Example 3 optionally includeswherein each of the plurality of shaft magnets is configured tomagnetically couple one of the plurality of housing magnets to transmita torque between the housing and the shaft, and wherein the plurality ofshaft magnets are each configured to uncouple from the one of theplurality of housing magnets, causing the shaft to rotate within thehousing when a threshold torque is reached.

In Example 5, the subject matter of Example 4 optionally includeswherein upon rotating the shaft when a threshold torque is reached, eachof the plurality of shaft magnets is configured to couple to a differentone of the plurality of housing magnets to transmit torque between thehousing and the shaft.

Example 6 is a torque limiting driver for driving a workpiece, thetorque limiting driver comprising: a housing comprising: a housing borecomprising a central axis; and a housing magnet located proximate thehousing bore; a shaft disposed within the housing bore, the shaftcomprising: a shaft magnet facing the housing and positioned to generatea magnetic coupling to the housing magnet to enable transmission of atorque between the housing and the shaft, wherein the magnetic couplingis configured to uncouple from the housing magnet allowing the shaft torotate about the central axis within the housing when a threshold torqueis reached; and a clutch connected to the shaft and configured totransfer the torque from the shaft to a workpiece unidirectionally.

In Example 7, the subject matter of Example 6 optionally includes ahandle coupleable to the housing to transfer a torque thereto.

In Example 8, the subject matter of any one or more of Examples 6-7optionally include a coupler removably coupleable to a distal end of theclutch, the coupler configured to releasably receive a driver therein.

In Example 9, the subject matter of any one or more of Examples 6-8optionally include a proximal bearing coupled to a proximal portion ofthe housing and a proximal portion of the shaft to enable rotation ofthe housing relative to the shaft.

In Example 10, the subject matter of any one or more of Examples 6-9optionally include a distal bearing coupled to a distal portion of thehousing and a distal portion of the shaft to enable rotation of thehousing relative to the shaft.

In Example 11, the subject matter of any one or more of Examples 6-10optionally include wherein the housing further comprises: a plurality ofhousing magnets disposed around a central bore of the housing.

In Example 12, the subject matter of Example 11 optionally includeswherein the shaft further comprises: a plurality of shaft magnetsdisposed within the shaft and, the shaft magnets coupleable with theplurality of housing magnets.

In Example 13, the subject matter of any one or more of Examples 6-12optionally include wherein the clutch includes a ratcheting mechanism.

In Example 14, the subject matter of any one or more of Examples 6-13optionally include the clutch further comprising: a driving memberconnected to a distal portion of the shaft, the driving member rotatablewith the shaft when the shaft receives a torque from the housing; and adriven member engaging the driving member, the driven member configuredto rotate the driven member using the torque when the torque is in afirst direction about the central axis and configured to rotateindependently of the torque when the torque is in a second directionabout the central axis.

In Example 15, the subject matter of Example 14 optionally includes thedriver member further comprising a driver releasably engageable with aworkpiece to transfer a torque from the driver to the workpiece.

In Example 16, the subject matter of any one or more of Examples 6-15optionally include wherein the clutch and the housing are not in contactwith each other.

In Example 17, the subject matter of any one or more of Examples 6-16optionally include the shaft further comprising: a shaft bore extendingaxially through the shaft.

In Example 18, the subject matter of any one or more of Examples 6-17optionally include wherein the shaft bore comprises a diameter thatvaries between a proximal end and a distal end of the shaft.

In Example 19, the subject matter of any one or more of Examples 6-18optionally include wherein an outer surface of the housing is axiallyfluted.

In Example 20, the subject matter of any one or more of Examples 6-19optionally include wherein the housing is configured to substantiallyshield magnetic fields from extending beyond the torque limiter.

Example 21 is a torque limiter comprising: a housing comprising ahousing magnet; and a shaft disposed within the housing, the shaftcomprising: a shaft magnet facing the housing and positioned to generatea magnetic coupling to the housing magnet to enable transmission of atorque between the housing and the shaft, wherein the magnetic couplingis configured to uncouple from the housing magnet allowing the shaft torotate when a threshold torque is reached.

In Example 22, the subject matter of Example 21 optionally includes aclutch connected to the shaft and configured to transfer the torque fromthe shaft to a workpiece unidirectionally.

In Example 23, the device, assembly, or method of any one of or anycombination of Examples 1-22 is optionally configured such that allelements or options recited are available to use or select from.

This overview is intended to provide an overview of subject matter ofthe present patent application. It is not intended to provide anexclusive or exhaustive explanation of the invention. The detaileddescription is included to provide further information about the presentpatent application.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings, which are not necessarily drawn to scale, like numeralsmay describe similar components in different views. Like numerals havingdifferent letter suffixes may represent different instances of similarcomponents. The drawings illustrate generally, by way of example, butnot by way of limitation, various embodiments discussed in the presentdocument.

FIG. 1 illustrates a three dimensional view of a tool and torquelimiter, in accordance with at least one example of this disclosure.

FIG. 2 illustrates an exploded isometric view of a torque limiter, inaccordance with at least one example of this disclosure.

FIG. 3 illustrates an isometric view of a housing and shaft of a torquelimiter, in accordance with at least one example of this disclosure.

FIG. 4 illustrates a torque limiter from a distal perspective, inaccordance with at least one example of this disclosure.

FIG. 5 illustrates a three dimensional view of a torque limiting driver,in accordance with at least one example of this disclosure.

FIG. 6 illustrates a three dimensional view of a torque limiting driver,in accordance with at least one example of this disclosure.

FIG. 7 illustrates a cross-sectional view of a torque limiting driver,in accordance with at least one example of this disclosure.

FIG. 8 illustrates a cross-sectional view of another torque limitingdriver, in accordance with at least one example of this disclosure.

FIG. 9 illustrates a cross-sectional view of a torque limiting driveracross section 9-9 of FIG. 8 , in accordance with at least one exampleof this disclosure.

FIG. 10 illustrates a perspective view of a surgical system, inaccordance with at least one example of this disclosure.

FIG. 11 illustrates a system schematic, in accordance with at least oneexample of this disclosure.

FIG. 12 illustrates a perspective view of a portion of a surgicalsystem, in accordance with at least one example of this disclosure.

DETAILED DESCRIPTION

Torque limiters are commonly paired with drivers for use for drivingfasteners, such as screws or bolts, in automotive, construction, andmedical industries. In some medical applications, screws or anchors thatare over-torqued (or driven too far into a bone or plate) can causedamage to the bone and/or the device being secured thereto (such as aplate). Screws that are under-torqued can become susceptible to backingout (or reversing out) of their bore, compromising the healing processand potentially causing secondary complications. Both under-torqued andover-torqued screws, therefore, can cause a large number of problemsduring or after a procedure. Within the surgical field, in particularwithin orthopedics, torque limiting screwdrivers and similar tools arecommonplace. For example, orthopedic surgeons performing a spine surgerywill often use a torque-limiting device to assist with insertion ofpedicle screws to assist in avoiding damage to vertebral bodies.

Torque limiters used in these and similar medical procedures require alow tolerance so that screws, anchors, and related components can beprecisely driven into bone (and/or other components, such as plates)without damaging the bone or other components, by driving to asufficient torque to ensure fastening thereto and prevent reversing orbacking out. This problem has been addressed in the past by mechanicaland electronic torque limiters. The current state of the arttorque-limiting handles utilize purely mechanical components to limitthe amount of torque that can transfer down a shaft. These mechanismscan lose their ability to precisely limit torque transfer over time andrequire recalibration or replacement. The available mechanical torquelimiting instruments provide limiting functionality due to the ease withwhich these tools go out of calibration. Certain mechanicaltorque-limiting handles can lose their ability to limit predeterminedtorques almost immediately. Constantly having to re-calibrate torquelimiting instruments is time consuming and also results in a lack ofconfidence in the tool, as the surgeons cannot count on the toolremaining calibrated. Other prior art includes electronic torqueindication methods, which can require electrical power for operation.Some of these torque limiters are adjustable so that they can berecalibrated regularly to ensure that they accurately and preciselylimit torque. However, these torque limiters can deviate from tolerancevery quickly requiring frequent and costly recalibration.

This disclosure addresses a problem with the available mechanical torquelimiting instruments involving a lack of accuracy, precision, andrequirement for regular calibration. To solve the calibration problemexhibited by known mechanical torque limiting instruments, the inventorslooked to use of magnetic fields to provide precise and repeatabletorque limiting characteristics in a surgical instrument. Thisdisclosure presents, among other things, a magnetic torque-limitinghandle that can use an arrangement of magnets to limit an amount oftorque transferred down a shaft. The arrangements of magnets can bereferred to as magnetic couplers. In magnetic couplers, torque can betransferred across an air gap by magnetic fields. One example of thisdisclosure can include two sets of magnets aligned in either a coaxialor face-to-face arrangement. One set of magnets can be attached to ahandle, and one set of magnets can be mechanically attached to a shaft.A user can fix the shaft into surgical components and hold and rotatethe handle. As the handle rotates, the two sets of magnets diverge fromone another. As they diverge, torque is created. When the designedtorque limit is exceeded, the magnets snap to their next position. Thisdisclosure presents a design that limits a torque using a magneticinterface, which is less susceptible to wear of torque-limitingcomponents and reduces calibration, repair, and replacement resulting incost and time savings.

FIG. 1 illustrates a three dimensional view of tool 12 and torquelimiter 10, in accordance with at least one example of this disclosure.

Torque limiter 10 can include body 14, proximal cover plate 16, distalcover plate 18, fasteners 20, and plate connector 21. Also shown in FIG.1 are workpiece 11 and orientation indicators proximal and distal.

Workpiece 11 can be a fastener, as shown in FIG. 1 , but can be anothertool, coupler, and the like, in other examples. In some examples,workpiece 11 can be configured for use in surgical procedures. In someexamples, workpiece 11 can be a machine screw with a hex head, as shownin FIG. 1 .

Tool 12 can be a wrench, driver, ratcheting driver, and the like,configured to engage with bits, shafts, and fasteners. Tool 12 caninclude a handle at a proximal end and a coupler at a distal endconfigured to engage fasteners, bits, and other tools. In one example,the coupler of tool 12 can be configured with a hex engagement.Connector 21 can be a coupler, such as a shaft, connected to proximalcover plate 16 and configured to couple transfer a torque to body 14. Insome examples, connector 21 can include a proximal end having a hexgeometry configured to engage common tools, such as the coupler of tool12.

Proximal cover plate 16 and distal cover plate 18 can be disposed atrespective proximal and distal ends of body 14, and can receivefasteners 20 to axially retain the components of body 14. As discussedfurther below, the distal end of body 14 can be configured to engageworkpiece 11 to transfer a torque from tool 12 to workpiece 11.

In operation of one example, a user can apply a torque to tool 12, whichcan be transferred to body 14 from connector 21. Body 14 can beconfigured to transfer the torque to workpiece 11 up to a thresholdtorque. When the threshold torque is reached, body 14 can allowconnector 21 to rotate relative to workpiece 11, limiting an amount oftorque that can be transferred from tool 12 to work piece 11. In someexamples, body 14 can limit the transfer of torque using coupledmagnets, such as permanent magnets, as described further below. In otherexamples, body 14 can limit the transfer of torque using electromagnets,and the like. The level of torque transferred by the handle to theworkpiece can be controlled through activation or deactivation ofelectromagnets within the torque limiter 10. In a torque limiter usingpermanent magnets, positioning of the magnets can be adjusted orremoval/replacement of individual magnets can be utilized to adjust thetorque level, among other mechanisms.

FIG. 2 illustrates an exploded isometric view of torque limiter 10,which can include body 14, proximal cover plate 16, distal cover plate18, fasteners 20, and coupler 22, and coupled magnets 24. Distal coverplate 18 can include central distal bore 23 and distal fastener bores25. Body 14 can include shaft 26 and housing 27. Coupled magnets 24 caninclude housing magnets 28 and shaft magnets 30. Housing 27 can includehousing fastener bores 32, housing bore 33, and housing magnet slots 34.Shaft 26 can include shaft magnet slots (not shown in FIG. 2 ), andcoupling bore 36. Proximal cover plate 16 can include proximal fastenerbores 38 and central proximal bore 39. Coupler 22 can include distalshaft 40, stop 42, and proximal shaft 44. Also shown in FIG. 2 are axisA and orientation indicators proximal and distal. Connector 21 is notshown as attached to proximal cover plate 16, but proximal cover plate16 can include connector 21 in the examples described in FIG. 2 .

Shaft 26, housing 27, proximal cover plate 16, distal cover plate 18,connector 21 (of FIG. 1 ), and coupler 22 can be comprised of metal,plastic, and the like. In some examples, shaft 26, housing 27, proximalcover plate 16, distal cover plate 18, and connector 21 can be comprisedof a non-ferric metal, such as aluminum, to avoid interfering withcoupled magnets 24, and that can transfer substantial torque withoutdeforming. Plastic and other non-metallics can also be used with similarbenefits.

Shaft 26 can be of a substantially cylindrical geometric shape, but canbe of other shapes in other examples. Housing 27 can be similarlygeometrically configured, but can include housing bore 32 that can be acylindrical bore sized to receive shaft 26 so that housing 27circumferentially encloses shaft 26, leaving distal and proximal ends ofshaft 26 exposed.

Shaft 26 can include magnet slots extending axially through shaft 26 andconfigured to receive shaft magnets 30, allowing shaft magnets 30 tomove axially within the slots, but limiting the movement of shaftmagnets 30 in all other directions relative to shaft 26. Similarly,housing 27 can include housing magnet slots 34 extending axially throughhousing 27 and configured to receive housing magnets 28, allowing shaftmagnets 30 to move axially within housing magnet slots 34, but limitingthe movement of housing magnets 28 in all other directions relative tohousing 27.

In some examples, axial movement of shaft magnets 30 within the slotscan be used to adjust the magnetic field between shaft magnets andhousing magnets 28, which can adjust a threshold torque transferrabletherebetween. In other examples, shaft magnets and housing magnets canbe held in place securely to prevent axial movement to help reducecalibration issues.

Distal fastener bores 25 of distal cover plate 18 can be alignable withhousing fastener bores 32 and proximal fastener bores 38 of proximalcover plate. Distal fastener bores 25, housing fastener bores 32, andproximal fastener bores 38 can be configured to receive fasteners 20,which can secure distal cover plate 18 and proximal cover plate 16 tohousing 27, and restricting axial movement of coupled magnets 24 withinhousing 27 and shaft 26. Once secured to housing 27, distal cover plate18 and proximal cover plate 16 can restrict axial movement of shaft 26relative to housing 27, leaving shaft 26 free to rotate within housingbore 33.

Coupling bore 36 can extend axially through shaft 26 and can beconfigured to receive a coupler, such as coupler 22, a workpiece, suchas workpiece 11 of FIG. 1 , and other tools, such as those configured toperform surgical procedures. Central distal bore 23 can be diametricallysized to be larger than coupling bore 36 so that a workpiece, tool, andthe like, can engage coupling bore 36 without interference from distalcover plate 18. Central distal bore 23 can also be diametrically sizedto accept stop 42, of coupler 22, within central distal bore 23,limiting axial movement of coupler 22, such as limiting insertion ofproximal shaft 44 into coupling bore 36.

Distal shaft 40 and proximal shaft 44 can extend distally andproximally, respectively, from stop 42, along axis A. Distal shaft 40and proximal shaft 44 can be configured to engage a workpiece, tool, andthe like. In some examples, distal shaft 40 and proximal shaft 44 can beconfigured to engage coupling bore 36 to transmit a torque from couplingbore 36 to a workpiece, such as work piece 11 of FIG. 1 .

In operation of one example, a user can transmit a torque from a tool,such as tool 12 of FIG. 1 , to connector 21 (of FIG. 1 ) and intohousing 27. Because housing magnets 28 are restricted from movingrelative to housing 27, the torque can be transferred from housing 27 tohousing magnets 28. Housing magnets 28 can be magnetically coupled toshaft magnets 30 within shaft 26. When housing magnets 28 begin torotate due to the received torque, a torque can be magneticallytransferred to shaft magnets 30 within shaft 26. Because shaft magnets30 can be secured to shaft 26, the torque transferred to shaft magnets30 can also be transferred to shaft 26. The torque can then betransferred from shaft 26 (through coupling bore 36) to a work piece,such as work piece 11.

When a second torque applied to housing 27 is larger than a thresholdtorque, housing magnets 28 will not be able to magnetically transfer thesecond torque to shaft magnets 30. A threshold torque can be a torquewhere the force required to move or rotate shaft magnets 30 and shaft 26with housing 27 is larger than the magnetic force coupling shaft magnets30 to housing magnets 28. The second torque can cause shaft 26 to rotatein the direction of the second torque relative to housing 27, preventingthe second torque from being transferred to a work piece, limiting anamount of torque that can be transferred through torque limiter 10. Whentorque is not transferred from shaft 26 because shaft 26 rotatesrelative to housing 27, each one of shaft magnets 30 can engage anotherof housing magnets 28 so that a torque that is lower than the thresholdtorque can again be transferred through torque limiter 10.

In some examples, shaft magnets 30 and housing magnets 28 can bereplaceable, so that the threshold torque is adjustable for torquelimiter 10. In other examples, housing 27 and housing magnets 28 and/orshaft 26 and shaft magnets 30 can be replaceable to adjust the thresholdtorque. The replacement housings and shafts may include magnets having aweaker or stronger magnetic field, or can include magnets havingdifferent spacing or different quantities. As shown in FIG. 2 , therecan be 4 of housing magnets 28 and shaft magnets 30. In some examples,there can be 1, 2, 3, 5, 6, 7, 8, 9, 10, and the like, of housingmagnets 28 and shaft magnets 30. In some other examples, housing magnets28 and shaft magnets 30 can have a different quantity. For example,there can be 4 of housing magnets 28 and 8 of shaft magnets 30.

FIG. 3 illustrates an isometric view of housing 27 and shaft 26. Housing27 and shaft 26 can be connected and can operate consistently with FIGS.1 and 2 ; however, FIG. 3 further shows shaft magnet slots 46. Shaftmagnet slots 46 can receive shaft magnets 30, allowing movement of shaftmagnets 30 in an axial direction, but limiting the movement of shaftmagnets 30 in every other direction relative to shaft 36.

FIG. 3 also shows shaft magnet slots 46 as being of the same quantity asand being radially aligned with housing magnet slots 34. This design canallow for the rotation of shaft 26 relative to housing 27 and quickrecoupling of housing magnets 28 to shaft magnets 30.

FIG. 4 illustrates torque limiter 10 from a distal perspective, inaccordance with at least one example of this disclosure. Torque limiter10 and its components can be connected and can operate consistently withFIGS. 1-4 . However; FIG. 4 additionally shows housing magnets 28 a-28 ddisposed within housing magnet slots 34 and shows shaft magnets 30 a-30d disposed in shaft magnet slots 46. FIG. 4 also shows housing magnets28 a-28 d and shaft magnets 30 a-30 d axially secured by distal coverplate 18.

FIG. 5 illustrates a three dimensional view of torque limiting driverassembly 60, in accordance with at least one example of this disclosure.FIG. 6 illustrates another three dimensional view of torque limitingdriver assembly without a bit or fastener, in accordance with at leastone example of this disclosure. FIGS. 5 and 6 are discussed belowconcurrently. Torque limiting driver 60 assembly (driver 60) can includehandle 62, torque limiter 64, clutch 66, coupler 68, bit (or driver) 70,and fastener 72. FIG. 5 also shows torque T and axis A.

In some examples, torque limiter 64 can be a magnetic torque limiter asdescribed above with respect to FIGS. 1-4 and as described in furtherdetail in FIGS. 7-9 below. Handle 62 can be a rigid member removablycoupleable to a housing of torque limiter 64. Handle 62 can be comprisedof rigid or substantially rigid materials, such as metals, plastics,composites, combinations thereof, and the like. In other examples,handle 62 can be integrally formed with torque limiter 64. Axis A can bea central longitudinal axis about torque limiter 64, and also abouthandle 62, clutch 66, coupler 68, and bit 70 in some examples.

Clutch 66 can be a unidirectional clutch, in some examples, configuredto transfer torque from torque limiter 64 to coupler 66 and therefore tobit 70 and workpiece 72. In some examples, clutch 66 can be aunidirectional clutch, or a clutch that is configured to transferrotation in only a single rotational direction about axis A, such as atrapped bearing, sprag clutch, ratcheting clutch, cam clutch, lockingroller clutch, locking needle clutch, and the like. In some examples, aproximal end of clutch 66 can be coupled to a distal end of a shaft oftorque limiter 64.

Coupler 68 can be a coupler (or quick coupler) configured to releasablyreceive a bit, such as bit 70. In some examples, coupler 68 can includea barrel and a sleeve axially movable relative to the barrel. In someexamples, the sleeve can actuate balls, or other movable members, tomove radially relative to the barrel and/or sleeve. A proximal portionof coupler 68 can be removably secured to a distal portion of clutch 66using an interference interface, in some examples, and a fastenedinterface in other examples. In some examples, coupler 68 can be sizedto receive bit 70 into an internal bore of the barrel and/or sleeve ofcoupler from a distal end of coupler 68. When inserted into the bore,coupler 68 can lock onto bit 70, preventing relative rotation or axialmovement of bit 70 relative to coupler 68 until the sleeve is actuated,axially for example, to release bit 70 from coupler 68.

Bit 70 can be a rigid shaft comprised of material such as plastics,metals, composites, and the like, and configured to transfer a torquefrom a proximal interface to a distal interface. The proximal interfaceof bit 70 can be configured to secure to coupler 68 (and to othercouplers in other examples) through a geometric profile such as ahexagonal, octagonal, slotted, or grooved interface. The distalinterface of bit 70 can include a tooled interface such as standard,cross recessed, hexagonal, hexolobular, square, and the like. The tooledinterface can be configured to interface with workpiece 72, which can bea bolt, screw, or other fastener.

In operation of some examples, for example during a procedure where itis desired to secure workpiece 72 to another components (such as a bone,plate, or other substrate), torque T can be applied to handle 62 in aclockwise direction about axis A. Handle 62 can transfer torque T totorque limiter 64, where magnets within torque limiter 64 can transfertorque T, via magnetic coupling, through torque limiter 64 and to clutch66 when torque T is below a threshold torque. When torque T is above athreshold torque, a shaft of torque limiter 64 can spin relative to ahousing of torque limiter 64 to provide a desired torque to workpiece 72and to help prevent over-torqueing of workpiece 72.

When torque T is below the threshold torque and is transferred to clutch66, clutch 66 can transfer torque T to coupler 68 and bit 70. However,clutch 66 cannot transfer torque in the opposite rotational direction(counter-clockwise about axis A). When torque T becomes equal to orgreater than the threshold torque, the coupled magnets within torquelimiter 64 can uncouple and the shaft and housing of torque limiter 64can rotate relative to each other, preventing the transfer of torque Tthrough torque limiter. When this happens, the internal magnets recoupleto different, adjacent magnets, which can cause unwantedcounter-clockwise rotation of bit 70 and workpiece 72. Because clutch 66is unidirectional, clutch 66 can help prevent counter-clockwise rotationof bit 70 during recoupling by allowing torque limiter 64 to rotatecounter-clockwise relative the coupler 68 and bit 70, or byfree-wheeling. This can help to allow workpiece 72 to be secured to acomponent at a desired torque. These details of driver 60 are discussedin further detail in the FIGS. below.

FIG. 7 illustrates a cross-sectional view of a torque limiting driver160, in accordance with at least one example of this disclosure. Driver160 can include torque limiter 164, clutch 166, and tool interface 170.Torque limiter 164 can include housing 174, shaft 176, distal bearing178, proximal bearing 180, housing magnets 182A and 182B, shaft magnets184A and 184B, and retaining ring 185. Clutch 166 can include drivenportion 188, driving portion 190, and rollers 192. Tool interface 170can include sleeve 194 and bit 196. Housing 174 can include housing bore175 and shaft 176 can include shaft bore 177. Distal bearing 178 caninclude inner race 1781, outer race 1780, and rollers 198. Proximalbearing 180 can include inner race 180I, outer race 1800, and rollers199. Also shown in FIG. 7 are diameters D1, D2, D3, and D4, axis A, andtorque T.

Housing 174 can be a rigid or semi-rigid body comprised of metals,plastics, composites and combinations thereof. Housing bore 175 can be abore having axis A (which can be a central longitudinal axis) andextending axially entirely through housing 174 in some examples. Inother examples, housing 174 can be closed at one or more ends of housing174. Housing bore 175 can be configured to retain shaft 176 therein. Theshape of housing bore 175 can be partially defined by distal andproximal bearings 178 and 180, respectively. Housing magnets 182A and182B can be located proximate housing bore 175 adjacent shaft magnets184A and 184B. Housing magnets 182A and 182B can be coupled to housingand in some examples releasably coupled to housing. Housing magnets 182Aand 182B can be secured to housing 174 using an interference fit in someexamples, and can be fastened, welded, glued, or otherwise affixed tohousing 174 in other examples. Shaft magnets 184A and 184B and housingmagnets 182A and 182B can be permanent magnets such as metallic magnets,rare-earth magnets, composite magnets, and the like.

In some examples, housing 174 can have a thickness sufficient tosubstantially shield magnetic fields produced by housing magnets 182and/or shaft magnets 184 from extending beyond driver 160. In someexamples, housing 174 can have a thickness of 0.5 millimeters (mm), 1mm, 2, mm, 3, mm, 4 mm, and the like. In some of these examples, housing174 can be comprised entirely or in part of materials that shieldmagnetic fields from propagation outside housing 174. For example,housing 174 can be comprised of ferromagnetic materials such as iron,nickel, cobalt, and alloys and combinations thereof. In one example,housing 174 can be comprised of mu-metal. In other examples, thethickness of housing 174 can be selected to provide a desired balance ofthe weight of driver 160 and the magnetic field emitted from driver 160beyond housing 174.

Housing flutes 186A and 186B can be two (or two of many in someexamples) axially extending channels of an outer surface of housing 174.Housing flutes 186 can provided an uneven exterior profile for improvedgrip and can help to reduce a weight of housing 174.

Shaft 176 can be a rigid or semi-rigid body comprised of metals,plastics, composites and combinations thereof. Shaft 176 can be disposedwithin housing 174 and within housing bore 175. Shaft 176 can berotatable within and relative to housing 174, which can be enabled bydistal bearing 178 and proximal bearing 180. More specifically, innerrace 1781 of distal bearing 178 and inner race 180I of proximal bearing180 can be coupled or secured to shaft 176 and outer race 1780 of distalbearing 178 and outer race 1800 of proximal bearing 180 can be coupledor secured to housing 174, such that rollers 198 and 199 help enablerotation of shaft 176 relative to housing 180. In some examplesretaining ring 186, which can be a cylindrical member having arelatively short height, can help position proximal bearing 180 relativeto housing 174 and shaft 176 and can help maintain the positions ofthese components.

In some examples, shaft 176 can include bore 177 having diameters D1,D2, D3, and D4, where each diameter can be sized based on an outerdiameter of shaft 176 at that portion of shaft 176. For example,diameter D1 is sized based on a size of proximal bearing 180, diameterD2 is sized based on a size of shaft magnets 184, diameter D3 is sizedbased on a size of distal bearing 178, and diameter D4 is sized based ona size of clutch 166. In this way, shaft 176 can be sized and shaped toreduce a weight of driver 160, helping to decrease power required tooperate driver 160, helping to decrease fatigue of an operator of duringa procedure or operation. In some other examples, shaft 176 can be solidand therefore may not include shaft bore 177.

Driven portion 188, driving portion 190, and rollers 192 of clutch 166can together form a unidirectional clutch. In the example of FIG. 7 ,clutch 166 can be a trapped roller clutch, but clutch 166 can be othertypes of unidirectional clutches in other examples, as discussed aboveand as shown in FIGS. 8 and 9 below. Driving portion 190 can be coupled(either releasably or fixedly) to a distal portion of shaft 176. In someexamples, shaft 176 can be insertable into driving portion 190. Drivenportion 188 can be engageable with driving portion 190 via rollers 192.Rollers 192 can be cylindrical rollers in some examples and can be ballsor spheres (as shown in FIG. 7 ) in other examples.

Tool interface 170 can include sleeve 194 and bit 196. Bit 196 can be atool configured to interface with fastener heads, as discussed abovewith respect to bit 70 of FIG. 5 . However, in the example of FIG. 7 ,tool interface 170 can be relatively short, axially, and can beintegrated with sleeve 194 to secure to clutch 166, such that a coupleris not required. In some examples, driver 160 can include a plurality ofbits 170 releasably coupleable to clutch 166, where the plurality caninclude bits of different tooled interfaces (e.g. cross-slot, standard,hex, etc.).

In operation of some examples, torque T can be applied to housing 174 oftorque limiter 164. Because outer races 1780 and 1800 and housingmagnets 182A and 182B are coupled to housing 174, torque T will betransferred to these components. When torque T is less than a thresholdtorque, housing magnets 182A and 182B can drive shaft magnets 184A and184B through a magnetic coupling, transferring torque T thereto. Becauseshaft magnets 184A and 184B are coupled to shaft 176, shaft 176 can bedriven by shaft magnets 184A and 184B, transferring torque T therewith.Inner races 1781 and 180I along with rollers 198 and 199 will alsorotate with shaft 176. As shaft 176 rotates about its central axis A,the distal portion of shaft 176 rotates, rotating driving portion 190 ofclutch 166.

When torque T has a clock-wise rotational direction about axis A,driving portion 190 engages rollers 192 and transfers torque T to drivenportion 188 to rotate driven portion 188 in a clock-wise rotationaldirection about axis A. Because tool interface 170 is coupled to drivenportion 188, tool interface 170 is also driven to rotate in a clock-wiserotational direction about axis A. Tool interface 170 can receive torqueT and transfer torque T to a fastener. However, when the torquetransferred to driving portion 190 is in a counter-clockwise rotationaldirection about axis A, the torque will not transfer to driven portion188 as driving portion 190 will free-wheel, or rotate relative to drivenportion 190. This can allow driver 160 to be used as a ratcheting orunidirectional driver. In some other examples, the driver 160 may notinclude a clutch 166 and the torque T is transferred in eitherrotational direction.

Driver 160 can be used to transfer torque T to a workpiece or fastenerin a clockwise rotational direction about axis A until a thresholdtorque is reached. In some examples, the threshold torque can be forexample, 0.01 newton meters (Nm), 0.1 Nm, 1 Nm, 10 Nm, 100 Nm, and thelike. Once torque T reaches or exceeds the threshold torque in aclock-wise rotational direction, housing magnets 182A and 182B decouplefrom shaft magnets 184A and 184B allowing housing 174 to spin relativeto shaft 176. When this happens, housing 174 rotates in a clock-wisedirection (the direction of torque T), and each of housing magnets 182Aand 182B can couple to another of shaft magnets. This decouplingprevents a torque T greater than the threshold torque from beingtransferred to a fastener or workpiece, which can set a desired torquefor the workpiece or fastener and can help prevent over-torque orover-tightening of fasteners to bones or plates, for example.

In an example where only two pairs of magnets are used, housing magnet182A can decouple from shaft magnet 184A allowing housing 174 to rotaterelative to shaft 176 and housing magnet 182A can couple to shaft magnet184B. In this example, housing 174 can turn approximately half a turn(when the magnets are spaced evenly about the circumference of housing174 and shaft 176 and when housing magnets 182 have the same polarity).In an example where only one pair of magnets is used, housing 174 canrotate about one revolution before the housing magnet (182A) recouplesto the same and only shaft magnet (184A). In other examples, there maybe more pairs of magnets, such as 3, 4, 5, 6, 7, 8, 9, 10, 20, and thelike. In these examples, when housing 174 decouples it can turn by theratio of one revolution over the number of pairs of magnets. Forexample, housing 174 would turn one quarter of a rotation when decoupledrelative to shaft 176 if driver 160 included 4 pairs of magnets.

In some examples where odd numbers of pairs of magnets are used, such as3, 5, 7, and 9, all of housing magnets 182 can be of the same magneticpolarity (e.g., north) and all shaft magnets 184 can be of the samemagnetic polarity (e.g., south—opposite of housing magnet 182 polarity).This prevents magnets of the same polarity from aligning duringrecoupling and helps maintain calibration of driver 160.

In other examples, where an even number of pairs of magnets are used,such as 4, 6, or 8 magnets, housing magnets 182 can be arranged inalternating polarity and shaft magnets 184 can be arranged inalternating polarity. This can increase the amount of torque that istransferrable between coupled magnets, because adjacent magnets on theopposite race will resist rotation due to opposing forces created bymagnets of the same polarity. For example, if there are four housingmagnets 182A-D and four shaft magnets 184A-D, each A and C magnet canhave a north polarity and each B and D can have a south polarity. Inthis arrangement, housing magnet 182A can be coupled to shaft magnet184B, housing magnet 182B can be coupled to shaft magnet 184C, housingmagnet 182C can be coupled to shaft magnet 184D, and housing magnet 182Dcan be coupled to shaft magnet 184A.

Consider, for example, coupling of housing magnet 182B and shaft magnet184C, where adjacent shaft magnets are 184B and 184D. Because shaftmagnets are 184B and 184D are of the same polarity as housing magnet182B, housing magnet 182B will receive opposing forces from shaftmagnets 184B and 184D, resisting uncoupling of housing magnet 182B andshaft magnet 184C (and therefore all of the coupled pairs). This canincrease the amount of torque that can be transferred between pairs ofmagnets.

In some examples, during driving or torqueing a workpiece, toolinterface 170 can be engaged with a workpiece, such that when athreshold torque is reached, tool interface 170 can remain engaged withthe workpiece. During the process of the magnets decoupling, housing 174spins in a clock-wise direction relative to shaft 176, and housing andshaft magnets 184 and 182 recouple (or couple to other magnets), shaft176 (and therefore tool interface 170 and the workpiece coupled thereto)can rotate in a counter-clockwise direction when shaft magnets 184recouple with housing magnets 182. This effect can be caused by themagnetic force between the pairs while coupling together with torque Tbeing continuously applied to housing 174. That is, housing 174continues to rotate clock-wise, so shaft 176 rotates counter-clockwise,where housing magnets 182 can recouple to the same shaft magnets 184, insome examples. This action can rotate tool interface 170 and thereforethe work piece in a counter-clockwise direction if not controlled,preventing a desired torque of the workpiece from being deliveredthereto.

This effect can also be caused by use of an arrangement of alternatingpolarity of shaft magnets 184 and alternating polarity of housingmagnets 182 (discussed above), because each shaft magnet cannot coupleto the adjacent housing magnet, but will instead be repelled by it. Inthis case, each housing magnet must rotate past the adjacent shaftmagnet to the next housing magnet of opposite polarity. In operation ofthis arrangement, torque T applied to housing 174 and resistance fromthe workpiece can cause recoupling to previously coupled pairs. However,clutch 166 can be used to help prevent this action.

Because clutch 166 is a unidirectional clutch, when shaft 176 rotates ina counter-clockwise direction during the recoupling of pairs of magnets,clutch 166 allows shaft 176 to rotate together with driving portion 190,but rollers 192 do not engage driven portion 188 and driving portion 190freewheels, or rotates relative to driven portion 188. This forceshousing magnets 182 to each couple to different shaft magnets 184 (inthe case where two or more pairs are used). This can help prevent therecoupling action from causing tool interface 170 to back the work pieceor fastener out, helping to maintain torque T just below the thresholdtorque or at a desired torque (torque set point). The design of driver160 can further allow another torque T that is above the thresholdtorque to be applied (as many times as desired) to the driver to ensurethe desired torque of the workpiece has been delivered.

Further, clutch 166 and housing 174 can be separated by gap G, which canbe 0.1 millimeter (mm), 1 mm, 10 mm, and the like. This separation canhelp prevent contact between housing 174 and clutch 166, which can helpto ensure that torque is not transferrable between housing 174 andclutch 166 except through shaft 176. In some examples, shaft 176 caninclude an undercut to ensure that clutch 166 cannot move proximallycloser to housing 174 and therefore cannot contact housing 174.

Though the examples above are described with respect to a torque in aclock-wise direction. Driver 160 can be configured to selectivelytransfer and deliver a torque in a counter-clockwise direction.

FIG. 8 illustrates a cross-sectional view of a torque limiting driver260, in accordance with at least one example of this disclosure.

Driver 260 can include torque limiter 264, clutch 266, and toolinterface 270. Torque limiter 264 can include housing 274, shaft 276,distal bearing 278, proximal bearing 280, shaft magnets 282A and 282B,housing magnets 284A and 284B, and retaining ring 286. Housing 274 caninclude housing bore 275 and shaft 276 can include shaft bore 277.Distal bearing 278 can include inner race 278I, outer race 2780, androllers 298. Proximal bearing 280 can include inner race 2801, outerrace 2800, and rollers 299. Also shown in FIG. 7 are diameters D1, D2,D3, and D4, axis A, and torque T. Driver 260 can be similar to driver160, except that clutch 266 can include driven portion 288, drivingportion 290, and pawls 292.

Driver 260 can operate consistently with driver 160 described in FIG. 7above; however, in driver 260, a pawl and gear interface can provideunidirectional clutching action. For example, pawls 292 can engage teethof driving portion 290 (as shown below in FIG. 9 in further detail). Inoperation, pawls 292 can transfer torque in a clockwise rotationaldirection about axis A and can allow driving portion 290 to freewheel orrotate relative to driven portion 288 when driving portion 290 rotatesin a counter-clockwise rotational direction about axis A.

Though not shown in FIG. 8 , clutch 266 can engage a coupler similar todriver 60 of FIGS. 5 and 6 where coupler 68 is securable to an outsidediameter of clutch 66.

FIG. 9 illustrates a cross-sectional view of torque limiting driver 260across section 9-9 of FIG. 8 , in accordance with at least one exampleof this disclosure. Driver 260 can include clutch 266 and shaft 276,which can include shaft bore 277. Clutch 266 can include driven portion288, driving portion 290, and pawls 292A and 292B. Driving portion 290can include ratchet 281, which can include teeth 283A-283N. Drivenportion 288 can include hinges 285A and 285B, ratchet bore 287, andouter race 289.

Shaft 276 can releasably (or fixedly in some examples) couple to drivingportion 290 at ratchet bore 287. In some examples, ratchet bore 287 canhave an octagonal cylindrical shape complementary with shaft 276 tosecurably engage with shaft 276 and to prevent relative rotationthereto. Teeth 283A-283N can be integrally formed with an internal raceof driving portion 290 and can extend radially from the race formingratchet 281, which can be a unidirectional gear.

Pawls 292A and 292B can be pivotably or hingeably coupled to outer race289 through hinges 285A and 285B, respectfully. Pawls 292A and 292B canbe hinged such that they hinge or pivot to allow teeth 283A-283N to passin a counter-clockwise rotational direction about axis A and engageteeth 283A-283N causing clockwise torque (such as torque T) to betransferred from teeth 283A-283N to pawls 292A and 292B and therefore toouter race 289 and allow driving portion 290 to drive driven portion 288in a clockwise rotational direction about axis A.

Because clutch 266 is a unidirectional ratcheting clutch, when shaft 276rotates in a counter-clockwise direction during the recoupling ofmagnetic pairs, as described above with respect to FIG. 7 , clutch 266allows shaft 276 to rotate together with driving portion 290, but pawls192 do not engage teeth 283A-283N allowing driving portion 290 tofreewheel. This can help prevent the magnetic recoupling action fromcausing a bit to back the work piece or fastener out, helping tomaintain torque T at a desired torque.

Though FIG. 9 is described as having a pawl hinged to an outer race ofclutch 266, pawls 292 can be on an inner race of clutch 266 in otherexamples, where the fixed teeth extend radially inward from outer race288. Similarly, more or fewer than two pawls can be included, such as 1,3, 4, 5, 6, and the like.

FIG. 10 illustrates a perspective view of surgical system 300, inaccordance with at least one example of this disclosure. System 300 caninclude robot 302, cart 304, table 306, and user interface 308. Robot302 can include mount 310, arm 312, and end effector 314. Also shown inFIG. 10 is patient 31 in a modified prone position.

Cart 304 can be a mobile or fixed cart or table configured to supportrobot 302 and/or user interface 308. In some examples, cart 304 caninclude a power source and/or control system for robot 302. Table 306can be a table, such as a surgical or operating table, configured tosupport and secure patient 31 in one or more positions during anoperation. In some examples, cart 304 and table 306 can be adjustable(e.g., height adjustable) either together or individually. In someexamples, cart 304 and table 306 can be secured to each other to preventrelative movement of cart 304 to table 306 during a procedure oroperation.

Arm 312 can be secured to cart 304 via mount 310. In some examples,mount 310 can be a rigid coupling and in other examples, mount 310 canbe a coupling providing one or more degrees of freedom of arm 312relative to cart 304. In one example, mount 310 can include a motor(e.g., a servo) and a bearing configured to rotate arm 312 relative tocart 304. Arm 312 can include one or more additional joints, eachconfigured to pivot or rotate to provide a total of two, three, four,and the like degrees of freedom of arm 312.

End effector 314 can be a distal portion of arm 312 and can beconfigured to releasably receive one or more tools, such as driver 160and/or 260 discussed above and driver 360 discussed below in FIG. 12 .In some examples, end effector 314 can be controlled via arm 312 anduser interface 308.

Robot 302 and user interface 308 can be in electric or electromagneticcommunication with each other. In some examples, user interface 308 canbe used to operate robot 302 and can include a control system thereforeas discussed in FIG. 11 below. In some examples, user interface canreceive data from robot 302 that can be displayed on a screen of userinterface 308. User interface 308 can also include input devices, suchas a keyboard, mouse, touchscreen, stylus, and the like, for receivinginputs from a user for controlling operations of robot 302. In someexamples, user interface 308 can be used to control robot 302 to drivefasteners into a plate or component secured to a patient, or a bone ortissue of a patient.

In operation of one example of surgical system 300, patient 31 can bepositioned on table 306 and cart 304 and robot 302 can be positioned inclose proximity to patient 31 and table 306. In some examples, asurgical procedure can be performed where an opening is created onpatient 31 allowing access to one or more bones of patient 31. In someexamples, a fastener or workpiece, such as a screw, can be loaded onto adriver coupled to end effector 314. User interface 308 can be utilizedby a user or physician to operate arm 312 of robot 302 to position thefastener at a desired location of the patient. In some examples, userinterface 308 can be used to rotate the driver and drive the fastenerinto a bone or into a plate or other component. Because the driver caninclude a torque limiting feature, as discussed above, robot 302 candrive the fastener into a plate, for example, at a desired torque and issubstantially prevented from over-torqueing the fastener into the plate.Because robot 302 does not have to track or determine the torque appliedto the fastener, the driver can help to simplify the design of robot302. In other examples, robot 302 can be autonomously operated by acontrol system to, for example, drive and torque a fastener using adriver coupled to end effector 314.

FIG. 11 illustrates a flow schematic, in accordance with at least oneexample of this disclosure. System 400 can include robotic arm 402,tracking system 408, and control system 410. Robotic arm 402 can includeend effector 404, including driver 406, which can be mounted on endeffector 404. Robotic arm 402 can be configured to allow interactivemovement and controlled autonomous movement of end effector 404.

Tracking system 408 can optionally include camera 412 or infrared sensor414. Tracking system 408 can use camera 412 or infrared sensor 414 totrack robotic arm 402, end effector 404, driver 406, a target object,and the like. In an example, tracking system 408 can be used todetermine a position or an orientation of driver 406. The position orthe orientation may be determined relative to a coordinate system orrelative to a target object. An example optical tracking device commonlyused for this type of application is the Polaris Optical Tracking Systemfrom Northern Digital of Waterloo, Ontario, Canada.

Control system 410 can optionally include user interface 416. In anotherexample, user interface 416 can be separate from control system 410 orcan be communicatively coupled to control system 410. In some examples,control system 410 can be used to determine a position or orientation ofdriver 406, such as using the position or the orientation of driver 406,a target object, and/or a coordinate system.

Tracking system 408 may determine a trajectory of driver 406 as it ismoved, such as from an interactive force applied to driver 406, endeffector 404, or robotic arm 402. Control system 410 may determine thatthe trajectory would cause robotic arm 402 or a portion of the roboticarm, end effector 404, and driver 406 to a position where a fastener canbe driven into a target, such as a plate to be secured to a patient. Inone example, once driver 406 has been positioned as desired, controlsystem 410 may establish an interaction zone using anatomical landmarksof the target object (e.g., a target plate) or identified locations ofthe target object (e.g., digitized locations). The tracking system 408may determine a position or an orientation of a target object relativeto the coordinate system. The position or the orientation of driver 406may be determined relative to the position or the orientation of thetarget object by the tracking system. In an example, the coordinatesystem is determined from the position or the orientation of the targetobject.

After driver 406 has been positioned relative to the target, driver 406can be rotated by robotic arm 402 to driver the fastener into the target(e.g., plate). A torque limiter of driver can limit the torque appliedby robotic arm 402 to driver 406 and therefore to the fastener to drivethe fastener into the plate at a desired torque and to help preventover-torqueing of the fastener into the target or plate. For example,magnets within a torque limiter of driver 406 can transfer torque, viamagnetic coupling, through the torque limiter and to a clutch when thetorque is below a threshold torque. When the torque is above a thresholdtorque, a shaft of the torque limiter can spin relative to a housing ofthe torque limiter to prevent over-torqueing of the fastener into theplate. By providing a robotic system including a driver that includes amechanical (magnetic) torque limiter, maintenance and service of therobotic system and torque limiter can be reduced because the magnetictorque limiter can require less-frequent calibration than other torquelimiters.

FIG. 12 illustrates a perspective view of end effector 314 of FIG. 10 ,in accordance with at least one example of this disclosure. End effector314 can include driver 360, flange 320, and arm 322.

Driver 360 can be consistent with drivers 160 and 260 discussed above,except that driver 360 may exclude a handle and may include provisionsfor releasably coupling to arm 322. For example, a proximal portion ofdriver 360 can be secured to a distal portion of arm 322 using, forexample, screws or bolts.

Flange 320 can be used to secure end effector 314 to arm 312 of robot302. In some examples, flange 320 can include holes for receiving boltstherethrough for releasably securing flange 320 to arm 312 of robot 302.In some examples, arm 322 can me rotatable independent of flange 320. Inother examples, end effector 314 can be rotatable as an assembly. In yetother examples, arm 312 can include a shaft therein (which can beflexible to accommodate the shape of arm 312) to rotation driver 360.

The devices, systems, and methods of this disclosure can offer severalbenefits over prior art. For example, torque limiter 10 uses magneticforces to limit torque, rather than mechanical, which can reducerecalibration, because there is little mechanical wear of the torquelimiting components. Also, because the methods of this disclosure usepermanent magnets to limit torque, the methods can be more reliable thanelectrical torque limitation methods of the prior art, which can berelatively expensive. The magnetic coupler of this disclosure canrequire less (re)calibration, and may not have other limitations of anelectronic device, such as the need to charge a battery.

The above detailed description includes references to the accompanyingdrawings, which form a part of the detailed description. The drawingsshow, by way of illustration, specific embodiments in which theinvention can be practiced. These embodiments are also referred toherein as “examples.” Such examples can include elements in addition tothose shown or described. However, the present inventors alsocontemplate examples in which only those elements shown or described areprovided. Moreover, the present inventors also contemplate examplesusing any combination or permutation of those elements shown ordescribed (or one or more aspects thereof), either with respect to aparticular example (or one or more aspects thereof), or with respect toother examples (or one or more aspects thereof) shown or describedherein.

In the event of inconsistent usages between this document and anydocuments so incorporated by reference, the usage in this documentcontrols.

In this document, the terms “a” or “an” are used, as is common in patentdocuments, to include one or more than one, independent of any otherinstances or usages of “at least one” or “one or more.” In thisdocument, the term “or” is used to refer to a nonexclusive or, such that“A or B” includes “A but not B,” “B but not A,” and “A and B,” unlessotherwise indicated. In this document, the terms “including” and “inwhich” are used as the plain-English equivalents of the respective terms“comprising” and “wherein.” Also, in the following claims, the terms“including” and “comprising” are open-ended, that is, a system, device,article, composition, formulation, or process that includes elements inaddition to those listed after such a term in a claim are still deemedto fall within the scope of that claim. Moreover, in the followingclaims, the terms “first,” “second,” and “third,” etc. are used merelyas labels, and are not intended to impose numerical requirements ontheir objects.

The above description is intended to be illustrative, and notrestrictive. For example, the above-described examples (or one or moreaspects thereof) may be used in combination with each other. Otherembodiments can be used, such as by one of ordinary skill in the artupon reviewing the above description. The Abstract is provided to complywith 37 C.F.R. § 1.72(b), to allow the reader to quickly ascertain thenature of the technical disclosure. It is submitted with theunderstanding that it will not be used to interpret or limit the scopeor meaning of the claims. Also, in the above Detailed Description,various features may be grouped together to streamline the disclosure.This should not be interpreted as intending that an unclaimed disclosedfeature is essential to any claim. Rather, inventive subject matter maylie in less than all features of a particular disclosed embodiment.Thus, the following claims are hereby incorporated into the DetailedDescription as examples or embodiments, with each claim standing on itsown as a separate embodiment, and it is contemplated that suchembodiments can be combined with each other in various combinations orpermutations. The scope of the invention should be determined withreference to the appended claims, along with the full scope ofequivalents to which such claims are entitled.

The invention claimed is:
 1. A robotic surgical system including atorque limiter, the system comprising: a robotic arm including an endeffector, the end effector comprising: a housing couplable including ahousing magnet enclosed within the housing; and a shaft couplable at adistal end to a driver, the shaft including a shaft magnet that ismagnetically coupleable with the housing magnet to transmit a torquebetween the housing and the shaft and configured to uncouple from thehousing magnet allowing the shaft and the shaft magnet to rotaterelative to the housing when a threshold torque is transgressed; atracking system operable to determine a location of the end effector;and a control system in communication with the robot arm and thetracking system, the control system configured to operate the endeffector of the robotic arm based on the location of the end effector.2. The robotic surgical system of claim 1, wherein the control system isconfigured to: transmit instructions to operate the robotic arm toposition a fastener attached to the shaft of the end effector withrespect to a patient.
 3. The robotic surgical system of claim 2, whereinthe control system is configured to: determine a trajectory of the shaftusing the tracking system; and transmit instructions to operate therobotic arm to position the fastener based on the determined trajectory.4. The robotic surgical system of claim 3, wherein the control system isconfigured to: transmit instructions to operate the robotic arm torotate the shaft to drive the fastener into the patient, wherein therobotic arm generates torque on the fastener limited by an interactionbetween the housing magnet and the shaft magnet.
 5. The robotic surgicalsystem of claim 1, further comprising: a user interface in communicationwith the control system and configured to transmit instructions to thecontrol system to operate the robotic arm.
 6. The robotic surgicalsystem of claim 1, further comprising: a clutch connected to the shaftand configured to transfer the torque from the shaft to the driverunidirectionally.
 7. The robotic surgical system of claim 6, furthercomprising: a coupler removably coupleable to a distal end of theclutch, the coupler configured to releasably receive a driver therein.8. The robotic surgical system of claim 7, further comprising: aproximal bearing coupled to a proximal portion of the housing and aproximal portion of the shaft to enable rotation of the housing relativeto the shaft; and a distal bearing coupled to a distal portion of thehousing and a distal portion of the shaft to enable rotation of thehousing relative to the shaft.
 9. The robotic surgical system of claim8, wherein the housing magnet further comprises: a plurality of housingmagnets disposed around a central bore of the housing; and a pluralityof shaft magnets disposed within the shaft and, the shaft magnetscoupleable with the plurality of housing magnets.
 10. The roboticsurgical system of claim 1, further comprising: a flange connected tothe housing and securable to the end effector.
 11. A robotic surgicalsystem including a torque limiter, the system comprising: a robotic armincluding an end effector, the end effector comprising: a housingcouplable including a housing magnet enclosed within the housing; and ashaft couplable at a distal end to a driver, the shaft including a shaftmagnet that is magnetically coupleable with the housing magnet totransmit a torque between the housing and the shaft and configured touncouple from the housing magnet allowing the shaft and the shaft magnetto rotate within the housing when a threshold torque is transgressed; atracking system operable to determine a location of the end effector;and a control system in communication with the robot arm and thetracking system, the control system configured to: operate the endeffector of the robotic arm based on the location of the end effector;and transmit instructions to operate the robotic arm to rotate the shaftto drive a fastener into a patient when the rotation provided by therobotic arm generates an arm torque that is lower than the thresholdtorque.
 12. The robotic surgical system of claim 11, wherein the controlsystem is configured to: transmit instructions to operate the roboticarm to position a fastener attached to the shaft of the end effectorwith respect to a patient.
 13. The robotic surgical system of claim 12,wherein the control system is configured to: determine a trajectory ofthe shaft using the tracking system; and transmit instructions tooperate the robotic arm to position the fastener based on the determinedtrajectory.
 14. The robotic surgical system of claim 13, furthercomprising: a user interface in communication with the control systemand configured to transmit instructions to the control system to operatethe robotic arm.
 15. The robotic surgical system of claim 11, furthercomprising: a flange connected to the housing and securable to the endeffector.
 16. A robotic surgical system including a torque limiter, thesystem comprising: a robotic arm including an end effector; a torquelimiter comprising: a housing securable to the end effector, the housingincluding a housing magnet enclosed within the housing; and a shaftcouplable at a distal end to a driver, the shaft including a shaftmagnet that is magnetically coupleable with the housing magnet totransmit a torque between the housing and the shaft and configured touncouple from the housing magnet allowing the shaft and the shaft magnetto rotate relative to the housing when a threshold torque is reached; atracking system operable to determine a location of the torque limiter;and a control system in communication with the robot arm and thetracking system, the control system configured to: operate the roboticarm based on the location of the torque limiter; and transmitinstructions to operate the robotic arm to drive a fastener into apatient when the rotation provided by the robotic arm generates an armtorque on the fastener limited by an interaction between the housingmagnet and the shaft magnet.
 17. The robotic surgical system of claim16, wherein the control system is configured to: transmit instructionsto operate the robotic arm to position a fastener attached to the shaftof the end effector with respect to a patient.
 18. The robotic surgicalsystem of claim 17, wherein the control system is configured to:determine a trajectory of the shaft using the tracking system; andtransmit instructions to operate the robotic arm to position thefastener based on the determined trajectory.
 19. The robotic surgicalsystem of claim 18, further comprising: a user interface incommunication with the control system and configured to transmitinstructions to the control system to operate the robotic arm.
 20. Therobotic surgical system of claim 16, further comprising: a clutchconnected to the shaft and configured to transfer the torque from theshaft to the driver unidirectionally; a coupler removably coupleable toa distal end of the clutch, the coupler configured to releasably receivea driver therein; a proximal bearing coupled to a proximal portion ofthe housing and a proximal portion of the shaft to enable rotation ofthe housing relative to the shaft; and a distal bearing coupled to adistal portion of the housing and a distal portion of the shaft toenable rotation of the housing relative to the shaft.